Page:Popular Science Monthly Volume 34.djvu/200

188 have a thickness of from six to eight miles. The bombardment would produce no other sensation than we now experience when a gentle breath of air fans our cheeks.

The picture which I have here presented is by no means the product of a mere fantastic flight of imagination, but a conclusion strictly warranted by mathematical facts, and necessary for the interpretation of the physical phenomena of nature.

But chemistry has to go yet one step further, in order to explain and render intelligible the phenomena of combination and affinity. We are driven to the conclusion that molecules are not the ultimate particles of matter, but are built up of still smaller bodies, the atoms. Thus, for instance, in a molecule of water we have two atoms of hydrogen united to one of oxygen, and all chemical processes have their source in the fact that the atoms of two or more molecules of different substances detach themselves and reunite again in a different fashion.

Now, in order to obtain a better idea of the manner in which the atoms are grouped in a molecule, we must look upon the latter as a duster, the various parts of which are combined by a well-regulated movement into a harmonious system. "We may well resort, for comparison, to a process within our observation, though on a far grander scale, which is admirably adapted for illustration. Let us look to our planetary system.

The planets, with the sun, represent a stable system, just as the atoms of a molecule represent such a one. In the case of our solar system, the mass of the planets, compared with that of the central body, is, of course, very insignificant. A far closer resemblance to our molecules is therefore presented by those systems of the stellar world in which two or more large bodies, of nearly the same size, revolve around their common center of gravity.

This parallel between atoms and planets, molecules and solar systems, opens before us a new and startling perspective. It affords us a glance into that unfathomable abyss which hides the mysteries of time and space, and holds in its dark recesses the very secrets of existence.

Astronomical science has shown that our sun, with the majority of the fixed stars visible to us, constitutes a great star-cluster, the diameter of which must be estimated by hundreds, if not thousands, of billions of miles. Of such star-clusters there exist a great many, which, in their turn again, form a still grander system, to which we also belong, and the boundaries of which are indicated by the outermost limits of the milky way.

How many of such galaxies may be hidden in the vastnesses beyond, in the bosom of infinite space, we will never know, for the light can only reach us from limited distances. Whatever may be beyond that very farthest nebula, the pale light of which